Secondary metabolites from Ganoderma lucidum and Spongiporus leucomallellus

The hydrodistillates and solvent extracts of the fruit bodies of Ganoderma lucidum (Fr.) P. Karst. and Spongiporus leucomallellus (Murril) A. David were investigated. The constituents in both oils comprised hydrocarbons, monoterpenes, sesquiterpenes, and fatty acids. Major volatiles of G. lucidum were trans-anethol, R-(-)-linalool, S-(+)-carvone and alpha-bisabolol, while the essential oil of S. leucomallellus contained relatively large amounts of R-(-)-1-octene-3-ol, R-(-)-linalool, 1-hepten-3-one and (Z)-nerolidol. From the n-hexane extract of G. lucidum, the steroid ester ergosta-7,22-diene-3beta-yl pentadecanoate could be identified. From S. leucomallellus two constituents showing structures of 3,4-seco-lanostane type triterpene acids were identified as (+)-23-oxo-3,4-seco-lanosta-4(28),7(8),9(11),24(31)-tetraene-3,26-dicarboxylic acid and (+)-20-hydroxy-23-oxo-3,4-seco-lanosta-4(28),7(8),9(11),24(31)-tetraene3,26-dicarboxylic acid, respectively. Cytotoxicity and antimicrobial activity of selected compounds were investigated using standard tests.     

Parametric and nonparametric FDR estimation revisited

Nonparametric and parametric approaches have been proposed to estimate false discovery rate under the independent hypothesis testing assumption. The parametric approach has been shown to have better performance than the nonparametric approaches. In this article, we study the nonparametric approaches and quantify the underlying relations between parametric and nonparametric approaches. Our study reveals the conservative nature of the nonparametric approaches, and establishes the connections between the empirical Bayes method and p-value-based nonparametric methods. Based on our results, we advocate using the parametric approach, or directly modeling the test statistics using the empirical Bayes method.     

Development of an insect model for the in vivo pathogenicity testing of yeasts

Conventional in vivo assays to determine the relative pathogenicity of yeast isolates rely upon the use of a range of mammalian species. The purpose of the work presented here was to investigate the possibility of using an insect (Galleria mellonella) as a model system for in vivo pathogenicity testing. The haemolymph of G. mellonella larvae was inoculated with PBS containing different concentrations of stationary phase yeasts of the genus Candida by injection at the last pro-leg. Larvae were incubated at 30 degrees C and monitored over 72 hours. Results indicate that G. mellonella can be killed by the pathogenic yeast Candida albicans and by a range of other Candida species but not to a significant extent by the yeast Saccharomyces cerevisiae. The kill kinetics for larvae inoculated with clinical and laboratory isolates of C. albicans indicate the former class of isolates to be more pathogenic. Differences in the relative pathogenicity of a range of Candida species may be distinguished using G. mellonella as a model. This work indicates that G. mellonella may be employed to give results consistent with data previously obtained using mammals in conventional in vivo pathogenicity testing. Larvae of G. mellonella are inexpensive to culture, easy to manipulate and their use may reduce the need to employ mammals for routine in vivo pathogenicity testing with a concomitant reduction in mammalian suffering.     

玉米螟赤眼蜂种群特异分子标记构建及其应用

赤眼蜂是我国乃至世界范围内应用最广的卵寄生蜂,其中玉米螟赤眼蜂Trichogramma ostriniae Pang et Chen是我国玉米种植区重要的天敌昆虫,但其不同的地理种群在生物防治效果上存在较大差异。为了有效利用玉米螟赤眼蜂的优势种群,有必要对其进行准确的鉴别。然而,采用传统形态学方法对同一种赤眼蜂的不同种群进行鉴别是非常困难的。本研究首先采用随机扩增多态性DNA(RAPD)标记对采自我国北京农科院、山东日照和山西太原的3个玉米螟赤眼蜂种群,进行了遗传差异分析,然后筛选了种群特异性位点,并通过克隆测序和引物设计构建了种群特异性分子标记,即序列特征性扩增区域(SCAR)标记。最后,利用SCAR标记对混合蜂群竞争试验结果进行了分子检测。该研究方法有助于玉米螟赤眼蜂优势种群的筛选,对于赤眼蜂的有效利用具有重要的意义。     

Permutation tests for random effects in linear mixed models

Inference regarding the inclusion or exclusion of random effects in linear mixed models is challenging because the variance components are located on the boundary of their parameter space under the usual null hypothesis. As a result, the asymptotic null distribution of the Wald, score, and likelihood ratio tests will not have the typical χ(2) distribution. Although it has been proved that the correct asymptotic distribution is a mixture of χ(2) distributions, the appropriate mixture distribution is rather cumbersome and nonintuitive when the null and alternative hypotheses differ by more than one random effect. As alternatives, we present two permutation tests, one that is based on the best linear unbiased predictors and one that is based on the restricted likelihood ratio test statistic. Both methods involve weighted residuals, with the weights determined by the among- and within-subject variance components. The null permutation distributions of our statistics are computed by permuting the residuals both within and among subjects and are valid both asymptotically and in small samples. We examine the size and power of our tests via simulation under a variety of settings and apply our test to a published data set of chronic myelogenous leukemia patients.     

Informative Dorfman screening

Since the early 1940s, group testing (pooled testing) has been used to reduce costs in a variety of applications, including infectious disease screening, drug discovery, and genetics. In such applications, the goal is often to classify individuals as positive or negative using initial group testing results and the subsequent process of decoding of positive pools. Many decoding algorithms have been proposed, but most fail to acknowledge, and to further exploit, the heterogeneous nature of the individuals being screened. In this article, we use individuals' risk probabilities to formulate new informative decoding algorithms that implement Dorfman retesting in a heterogeneous population. We introduce the concept of "thresholding" to classify individuals as "high" or "low risk," so that separate, risk-specific algorithms may be used, while simultaneously identifying pool sizes that minimize the expected number of tests. When compared to competing algorithms which treat the population as homogeneous, we show that significant gains in testing efficiency can be realized with virtually no loss in screening accuracy. An important additional benefit is that our new procedures are easy to implement. We apply our methods to chlamydia and gonorrhea data collected recently in Nebraska as part of the Infertility Prevention Project.     

Exposure of the Human Body to Professional and Domestic Induction Cooktops Compared to the Basic Restrictions

We investigated whether domestic and professional induction cooktops comply with the basic restrictions defined by the International Commission on Non‐Ionizing Radiation Protection (ICNIRP). Based on magnetic field measurements, a generic numerical model of an induction cooktop was derived in order to model user exposure. The current density induced in the user was simulated for various models and distances. We also determined the exposure of the fetus and of young children. While most measured cooktops comply with the public exposure limits at the distance specified by the International Electrotechnical Commission (standard IEC 62233), the majority exceeds them at closer distances, some of them even the occupational limits. The maximum current density in the tissue of the user significantly exceeds the basic restrictions for the general public, reaching the occupational level. The exposure of the brains of young children reaches the order of magnitude of the limits for the general public. For a generic worst‐case cooktop compliant with the measurement standards, the current density exceeds the 1998 ICNIRP basic restrictions by up to 24 dB or a factor of 16. The brain tissue of young children can be overexposed by 6 dB or a factor of 2. The exposure of the tissue of the central nervous system of the fetus can exceed the limits for the general public if the mother is exposed at occupational levels. This demonstrates that the methodology for testing induction cooktops according to IEC 62233 contradicts the basic restrictions. This evaluation will be extended considering the redefined basic restrictions proposed by the ICNIRP in 2010. Bioelectromagnetics 33:695–705, 2012. © 2012 Wiley Periodicals, Inc.     

奶山羊PIS遗传缺陷基因的检测及应用

文章旨在建立一种奶山羊无角间性综合征(Polled intersex syndrome,PIS)遗传缺陷基因检测方法。根据PIS基因序列(AF404302)分别设计PIS、PIS+、NEI 3对扩增引物,利用PCR技术鉴定奶山羊PIS遗传缺陷基因型。基因型为PIS PIS+与PIS PIS+的表型正常个体分别扩增出(141,300 bp)和(141,449,300 bp)的片段组合,隐性纯合间性山羊(PIS+PIS+)扩增出(449,300 bp)的片段组合。利用该方法检测一个224个体的奶山羊群体,结果显示:PIS PIS、PIS PIS+和PIS+PIS+个体分别为70、150和4个。该群体中PIS PIS+基因型频率高达66.9%,PIS+基因频率为35.3%,其子代群体出现间性山羊的可能性将超过12%。文章所开发的奶山羊PIS遗传缺陷基因检测方法可直接准确判别种公羊的基因型,从而避免缺陷基因携带者种公羊的使用。该方法易操作且准确性高,对奶山羊的标记辅助选择及奶山羊产业的健康发展具有重要意义。     

Getting a head start: the importance of personal genetics education in high schools

With advances in sequencing technology, widespread and affordable genome sequencing will soon be a reality. However, studies suggest that "genetic literacy" of the general public is inadequate to prepare our society for this unprecedented access to our genetic information. As the current generation of high school students will come of age in an era when personal genetic information is increasingly utilized in health care, it is of vital importance to ensure these students understand the genetic concepts necessary to make informed medical decisions. These concepts include not only basic scientific knowledge, but also considerations of the ethical, legal, and social issues that will arise in the age of personal genomics. In this article, we review the current state of genetics education, highlight issues that we believe need to be addressed in a comprehensive genetics education curriculum, and describe our education efforts at the Harvard Medical School-based Personal Genetics Education Project.